VII. RECORDING INSTRUMENTS. 705 



mines also for the subsequent measuring of the curve the adjusting of a 

 transparent scale, with the co-ordinate lines of time and height. 



IV. Finally, the mechanical execution of the apparatus, which comes from 

 the establishment of Herr Wanke, is deserving of attention. 



2873b. Photographic Thermograph, as employed at the 

 seven observatories of the Meteorological Committee. Described, 

 Report of Meteorological Committee of Royal Society for 1867. 



The Meteorological Committee of the Royal Society. 



2874. Electric Registering Anemometer with momentary 

 contact contrivance. 



Prof. Osnaghi, Imperial Central Meteorological Insti- 

 tute, Vienna. 



The apparatus registers each kilometre by marks impressed on a slip of paper 

 moved by clockwork. 



2875. Wind-Current Autograph, or Registering Appa- 

 ratus. John G. Schoen. 



This " Wind-Current Autograph " marks, or registers, continuously and 

 correctly, on a strip of paper moved \>j clockwork, the motion or direction of 

 the currents of wind in such a manner that the time is indicated as the 

 abscissa, and the angle of elongation of the weather-vane towards the north 

 shown at every particular moment, as the ordinate. 



2876. Electrical self-recording Anemometer and 

 Printing Apparatus, invented by the Exhibitor. 



J. E. If. Gordon. 



The figures on the left hand side of the paper give the hours, those on the 

 right the direction of the wind at each quarter of an hour, while for every 

 mile of wind that passes over the cups on the roof a dot is made in the 

 centre of the paper. The number of dots between any two consecutive 

 figures is the velocity in miles per hour for that hour. The communication 

 with the roof being made by electricity no shaft is required. 



2877. Automatic Light Registering Apparatus. 



A. Salted paper. F. Insolator. 



B. Silver nitrate solution. Gr. Cover for insolator. 



C. Trough for silvering paper. H. Clock. 



D. Drying reel. K. Battery. 



E. Dark box. L. Punch. 



M. Reading-off apparatus : 



a. Drum. /./. Stands for platinum wires. 



b. Graduated strip. g. Bunsen burner. 



c. Stand. h. Lens. 



d. Sodium carbonate. k. Spirit lamp. 



e. e. Platinum wires. 



Prof. H. E. Roscoe, F.R.S. 



This method depends on the fact that the depth of colour produced on a 

 properly prepared chloride of silver paper is directly proportional to the 

 intensity of the light multiplied by the time of exposure. 



40075. Y y 



